The present invention relates generally to an automatic answering telephone set or apparatus which is capable of responding to a remote manipulation or control access made, for example, from an external public telephone set by using a password number (i.e. numerical password) to thereby reproduce a verbal or oral message or note recorded during the subscriber's absence so that an authorized person calling currently can aurally know the message. More particularly, the present invention is concerned with an automatic answering telephone set which can perform operation for verifying through collation the password number established previously for enabling the remote control or manipulation of the telephone set within a short time span while ensuring effectively the secrecy and security.
As the automatic answering telephone set designed to reproduce a message aurally comprehensibly in response to a request or access made from an external telephone apparatus by using a password number, there is generally known such automatic answering telephone sets in which specific remote control signal or DTMF signal is made use of as the password for authorizing the remote manipulation or control of the telephone set.
However, when the remote control signal is utilized as the password, a commander device dedicated to this end is required, which device has to be carried by the subscriber or authorized user whenever he or she leaves the place where telephone set is installed, incurring inconvenience in the use of the automatic answering telephone set. On the other hand, in case the DTMF signal is employed as the password, the remote control of the automatic answering telephone set can not be permitted from the other telephone set than that of a push-phone type, i.e. telephone set equipped with a push-button dial, to disadvantage.
For coping with the problems mentioned above, there has already been proposed a system which can operate without resorting to the use of the particular remote control signal or DTMF signal. This system will be described below in some detail for having a better understanding of the present invention.
According to the proposed system, the automatic answering telephone set is provided with a voice synthesizing unit and a voice detector, wherein a request of a calling party for reproduction of a message through remote control via a telephone circuit or line (or channel in more general sense) is answered by the voice synthesizing unit which phonates sequentially figures or numerals of "0" to "9", inclusive, one after another for the purpose of inquiring of the calling party, while the voice detector detects presence or absence of voice replies inputted by the calling party in response to the inquiries, whereon the numerals for which the voice replies have been detected (i.e. numerals of input password number) are compared with those of a password number established previously (hereinafter referred to as the preestablished password number). Only when coincidence is resulted from the comparison, the remote manipulation or control for inputting of a message to the telephone set as well as reproduction of a message is permitted.
FIG. 6 of the accompanying drawings shows a flow chart for illustrating a password number verification procedure adopted in a prior art automatic answering telephone set in which a voice signal is employed.
In the case of the automatic answering telephone set under consideration, a password number "A" is previously established by using a number n of numerals selected from "0" to "9" (where n represents an integer given by 1&lt;n&lt;9). To say in another way, the preestablished password is constituted by a string of n numerals or figures (i.e. an n-digit number).
Referring to FIG. 6, a voice synthesizing unit incorporated in the automatic answering telephone set phonates sequentially ten numerals of "0" to "9" (generally represented by m) in this order in response to a calling party's request for reproducing a message through the remote control via the telephone line, whereon phonation of the abovementioned ten numerals of "0" to "0" are repeated a number of times which corresponds to the number of the numerals contained in the preestablished password number "A" (i.e. n times in the case of this example), as indicated at steps 61 and 62 in FIG. 6. Every time the ten numerals are phonated successively and discretely by the voice synthesizing unit, detection is performed by the voice detector as to which of the ten numerals the calling party inputs voice reply for. Only when the voice reply is detected (step 63), the relevant numeral is stored. In this way, there are stored n numerals in the order of the voice replies made by the calling party.
More specifically, the calling party will reply with, for example, "YES" every time he or she encounters the numeral constituting the preestablished password "A" in the course of hearing the numerals of "0" to "9" generated by the voice synthesizing unit. By repeating this operation n times corresponding to the n numerals selected from "0" to "9" for constituting the preestablished password "A", the automatic answering telephone set can generate an input password number "B" constituted by a series of n numerals for which the calling party has replied in the corresponding order (steps 62, 63, 64, 65 and 66).
Subsequently, the input password number "B" is compared with the preestablished password number "B" (step 67), wherein when the comparison results in coincidence, it is decided that the password number is correctly inputted (step 68). Thus, the automatic answering telephone set is changed over to a remote control or manipulation mode (step 69), whereby the calling party is allowed to perform the remote control via the telephone line for reproduction and hearing of a message, if any.
On the other hand, when the comparison shows that the inputted password number "B" differs from the preestablished password number "A" at the step 67, decision is made that the inputted password number is incorrect (step 70). In that case, the voice synthesizing unit of the automatic answering telephone set may phonate, for example, "Password is not correct. Please reply correctly.", whereon the operation described above may be repeated. Unless the correct password number is inputted even after repetition of the abovementioned operation for a predetermined number of times or even after lapse of a predetermined time, the telephone line is released to thereby disenable the remote control, as indicated at a step 71.
As will now be understood, the prior art automatic answering telephone set is certainly capable of reproducing a recorded oral message with the aid of the password number.
At this juncture, it should be mentioned that the remote control or manipulation is never restricted to the reproduction and hearing of the oral message recorded during the subscriber's absence but may be performed for a variety of functions and operations such as fast-feeding for reproduction, rewinding for reproduction, erasing of record in an automatic responsive recorder, alteration of message to be answered in response to the call, setting and resetting of transfer function, room monitor function and others.
In conjunction with the automatic answering telephone set known heretofore, it is however noted that the voice synthesizing unit has to phonate the series of numerals of "0" to "9" repeatedly for n times for verification of the password number constituted by n numerals (i.e. password of an n-digit number), while the calling party must select the numerals constituting parts of the password number "A" in the course of repetitive generation of the abovementioned numeral series and reply with voice every time the relevant numeral is encountered. Under the circumstances, there arises a problem that a lot of time is taken for the verification of the password number.
Besides, an additional problem is pointed out recently that an unauthorized person who could not inherently know the password number can manipulate or control remotely the automatic answering telephone set.